Measurement of microwave signals, such as continuous wave (CW) microwaves, is an integral part of many theoretical experiments and commercial systems. For example, CW microwave measurements are involved in ground penetrating detection, non-destructive testing and medical imaging. Analyzing the phase information of the microwave signals is important for estimating electric permittivity and conductivity profiles of measured materials or medical samples. However, traditional time-domain microwave sensing systems employ complicated equipment, such as vector network analyzers (VNAs), to measure in-phase and quadrature components of a microwave signal received at an antenna. Such a conventional system is shown in FIG. 1.
FIG. 1 is block diagram illustrating a conventional system for measuring microwave signals. A system 100 may include an antenna 102 coupled to a vector network analyzer 104, which may provide signals to a personal computer 106 for analysis and storage. However, the vector network analyzer 104 is an expensive and complicated tool that is difficult for use without extensive training.
One conventional solution is the use of solid state devices such as a spintronics or a semiconductor sensor to detect microwave signals and obtain phase information regarding the microwave signals. However, solid state devices in conventional setups take far longer to complete a phase measurement compared to a system using a vector network analyzer, such as the system 100 of FIG. 1. That is because with a solid state device, an operator must tune a phase shifter through a series of values and perform a computer fitting of the measured alternating interference fringes of rectified voltage in order to determine phase information of the microwave signal.